Scientists have uncovered the exact genetic sequence of E. coli O157, the bacterium which poisons tens of thousands of people every year and killed 21 in Scotland in 1996.

Escherichia coli 0157 is a particularly nasty organism

Pennington Report, 1997

The bug's "life code" was read by a team at the Genome Centre of Wisconsin, US, led by Professor Nicole Perna. The researchers report their work in the journal Nature.

E. coli O157 first came to public attention in 1982 when people across several states in the US were poisoned by contaminated hamburgers. The Wisconsin team used a sample preserved from this outbreak.

"We hope by developing a better understanding of exactly how this organism causes disease, we can find way to treat it," Professor Perna told BBC News Online. "At the moment we have no methods for treating E. coli O157 infections. Essentially, all we can do is supportive therapy - rehydration and monitoring," she added.

Crucial differences

The Wisconsin study answers questions for food safety scientists, according to Professor Hugh Pennington of Aberdeen University, author of the report on the fatal 1996 Scottish outbreak.

"The study tells us the differences between E. coli O157 and the E. coli found in our stomachs, which, under normal circumstances, is harmless. What we have to do now is work out what the differences mean," he told BBC News Online.

The new information could lead to a better test for E. coli O157. "We now have a complete list of the genes present in this organism and they can be used to develop sensitive DNA-based diagnostic techniques," Professor Perna said.

It said: "Infection in humans can cause anything from very mild or indeed no symptoms to very severe complications, even death. Infection is particularly dangerous for vulnerable groups such as elderly people or young children."

On Monday, a young British boy, who suffered brain damage after contracting an E. coli O157 infection during a school trip to a farm, secured £2.6 million in agreed damages.

Seven-year-old Tom Dowling fell into a coma after becoming infected during a trip to the farm in Hertfordshire in 1997 and now requires a wheelchair and 24-hour care.

His award was approved by the High Court in London after the owners of the farm and the local authority which ran his school admitted 95% responsibility for his injuries.